I don't think the author's intent is to show a healthy relationship. Relationships with yandere types are often toxic and unhealthy.
The movie was about an abusive relationship not a healthy one and how to try and get away but it wasn't that good of a movie that really implemented it well but just give a message about it. I do know that relationships like these aren't good and can be crazy and toxic.
Can you give me the title? Reading your comment make me interested
It's an okay movie but the title is: reviving ophelia
I just watched a movie in my health class today about abusive relationships and it was almost the same with the whole checking the phone and blaming and getting possessive.
Other than that they really gave me the shivers in like an excited yet creeper out way !